The short takeoff/vertical landing (STOVL) variant of the F-35 Joint Strike Fighter that Lockheed Martin [LMT] is making for the Marine Corps flew faster than the speed of sound for the first time last week, the company said yesterday.

On June 10, the aircraft accelerated to Mach 1.07 (727 miles per hour) on the first in a long series of planned supersonic flights. The supersonic milestone was achieved on the 30th flight of the F-35B known as BF-2.

During the flight, Marine pilot Lt. Col. Matt Kelly climbed to 30,000 feet and accelerated to Mach 1.07 in the off-shore supersonic test track near Naval Air Station Patuxent River, Md.

According to Lockheed Martin, future testing will gradually expand the flight envelope out to the aircraft’s top speed of Mach 1.6, which the F-35 is designed to achieve with a full internal weapons load of more than 3,000 pounds. All F-35s are designed to launch internal missiles at maximum supersonic speed, as well as launch internal guided bombs supersonically.

BF-2 is the third F-35 to achieve supersonic flight. Two F-35A conventional takeoff and landing variants also have broken the sound barrier.

Three F-35 variants are under development–the A-model conventional take-off/landing variant to replace Air Force F-16s and A-10s; the STOVL B-model to replace Marine Corps AV- 8B Harriers and F/A-18s; and the C-model carrier variant to replace Navy F/A-18s.